Method of treating ballast-wires for electric lamps.



U ITED STATES PATENT OFFICE.

HENRY NOEL POTTER, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGEWESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

METHOD OF TREATING BALLAST-WIRES FOR ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 699,232, dated May 6,1902. Application filed July 14,1900- Serial No. 23,651. (No specimens.)

To ctZZ whom it may concern: I

Be it known that I, HENRY NOEL POTTER, a citizen of the United States,residing at Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Methods ofTreating Ballast-Wires for Electric Lamps, of which the following is aspecification.

My invention relates to electric lamps of the type in which thelight-giving element or glower is a conductor of electricity only whenhot, and particularly to the devices employed in connection with theglowers for compensating for their decrease in resistance as theirtemperature increases.

The object of my invention is to provide a method of treating ballastdevices of the character above indicated which may be easily practicedand which will provide a ballast device the temperature of which willincrease uniformly throughout its length under the action of an electriccurrent passed through it.

In the use of ballast devices consisting of freely-stretched iron wiresupported in a chamber filled with hydrogen gas, which is a form that Ihave heretofore generally employed, I find that even the mostaccuratelydrawn wire does not heat up evenly through-' out its lengthupon the passage of a given current, and even though the wire be ofexactly uniform diameter and density throughout, so that its specificelectrical resistance and also its resistance per unit of length areabsolutely constant, yet the location of the wire in the ballast-chamberas regards its dis tance from the walls of the chamber and also from thesupporting-wires and other bodies 7 as the correction afforded by theiron ballast is limited as regards the range of temperature and has asharply-defined temperature at which its usual correction begins, it isdesirable that'the entire length of wire, or as much of the length aspossible, should attain the critical temperature under the action of agiven current.

I have discovered and demonstrated by experiment that iron ballast wiresmay be treated by heating them in the presence of a suitable compoundcontaining iron, so that the iron will be deposited on the wire in suchmanner as to insure the desired uniformity of temperature and correctiveeffect throughout its length. The treatment that I have foundeflicacious in practice involves the use of an organic compound ofironsuch, for example, as that formed by passing carbon monoxid (CO)over finely-divided iron which is heated to a temperature of from 40 tocentigrade-the gaseous compound thus formed being iron tetracarbonylFe(OO) This gaseous compound when heated to a temperature of from 200 to300 centigrade is decomposed and deposits its iron upon the heatedsurface. In order to treat the ballast-wire, which is mounted in aninclosin'g chamber, the air is exhausted from the chamber, and thelatter is then filled with the above-mentioned gas. Current is caused totraverse the iron wire for such length of time as to raise its temperature sufliciently high to decompose the gas and produce a deposit ofiron therefrom upon.

the wire. If different temperatures are produced in different parts ofthe wire, the hotter portions, which have the greater resistance, willreceive the greater amount of deposit, and consequently the adjustmentafiorded by the deposit will be such as to insure an even resistance andtemperature throughout the length of the wire.

I desire it to be understood that other compounds of iron which willgive up their iron when heated may be employed in lieu of the compoundabove specified without departing from my invention.

For example,pentacarbonyl,Fe(00),,whicl1 is a liquid that boils at 103centigrade, or heptacarbonyl, Fe,(OO) which is a solid of comparativelylow melting-point, may be employed, if desired, providing the conditionsattending the practice of the method in any given case make it feasibleto utilize such material. The use of one or the other of thelast-mentioned compounds may be found more advantageous than the use oftetracarbonyl for the reason that they may be more easily stored andhandled than a gaseous compound.

I claim as my invention 1. The method of treating ballast-conductors forelectric lamps which consists in heating said conductors in the presenceof a compound containing as one of its constituents, the material ofwhich the ballast-conductors are composed to such temperature as toefiect a deposit of the material upon the conductors.

2. The method of treating iron ballast-conductors for electric lampswhich consists in heating the conductors in the presence of a compoundcontaining iron to such temperature and for such a period of time aswill efiect decomposition of the compound and a deposit of the irontherefrom upon the conductors.

3. The method of treating iron ballast-wires consisting of heating themin an inclosing chamber containing a compound of iron to such degree andfor such a period of time as to elfect decomposition of such compoundand a deposit of iron on the ballast-wires.

4. The method of treating ballast-wires for electric lamps whichconsists in inclosing a wire in a chamber containing an organic compoundof iron and heating the wire to such temperature and for such a periodof time as will effect decomposition of the compound 25 and deposit theiron upon the wire.

5. The method of treating an iron ballastwire for electric lamps whichconsists in inclosing such wire in a chamber containing an organiccompound of iron and passing an 0 electric current through said wire ofsuch volume and at such pressure as will efiect a deposit of ironthereon in accordance with the resistance of the different portionsthereof.

In testimony whereof Ihave hereunto sub- 35

